Im not sure why this happens but even when I go into input settings and try to change it, it still doesn't work.It only seems to jump when pressing the left or right arrow keys(which is to move left and right) while pressing the jump keys.Any idea on why this is happening?

I used Unity 2 back in the day, and I've never had this problem, so I believe the man above is correct. However things have changed, so I don't know. If fixing the typo doesn't get rid of the error, try going to Edit->Project Settings->Input to fix it. Just go through the drop down boxes in the top left corner.